some 09 stuff from yami site KINDA

[Laban]

Infinite Range CVT? This is where your assumption may be wrong. An snowmobile transmission is infinite between it's starting ratio and ending ratio. But it's does have an starting ratio and ending ratio. With more torque you can have an higher lower ratio(meaning less torque multiplication) to achieve the same rate of acceleration giving you more gear on top.

A snowmobile is definitely not a Inifinite range CVT. That was just an example to show that torque is not what's matter the most since there's a gearbox, gearings between the engine and the driveshaft.

Your comparison of an 19,000 rpm 900 Hp F1 engine vs an 3,000 RPM 500 HP truck engine is not valid as they are not the same HP, the point many of us have been trying to make.

They're not the same hp in this example, but the F1 engine has much lower torque. Are you now saying that this isn't as important as hp ?

An modern analagy would be Lemans Racing. The Audi Diesel makes about 650hp and 800 lbs of Torque, absoultely crushing the F1 based racers that have similar HP but much lesser torque. Audi can run larger gears, giving up not that much in accel(limited by traction anyways - just like sleds) but still accelerating faster than the F1 based cars, but crushing them on top by I think 20MPH from an press release I read the other day.

The Audi Diesel can win Le-Mans because it's using much less gas (or diesel in this case). The Audi Diesel wouldn't stand a chance against a F1 car on a F1 track. Even if they put it in a F1 chassi.

 

[ZAKSTANG]

horsepower is a function of torque....build a motor with a broad torque curve and you will much happier than one that is "peaky" so to speak....hence the reason 4stroke yamis are so much better than their 2 stroke counterparts....just my opinion..but to say "torque doesn't matter" shows that you dont understand how engines work...torque definitely does matter....

 

[QCRider]

The fact is that snowmobile riding is a lot closer to Lemans than it is to an F1 race. F1 motors only need to last 2 weekends, and fairly often they aren't even able to do that.

The ONLY reason F1 motors run at the RPM they do is because the FIA has a limit on displacement. Why do you suppose they limit displacement? Because it is the EASIEST way to make more Torque and therefore more Horsepower.

 

[Laban]

horsepower is a function of torque....build a motor with a broad torque curve and you will much happier than one that is "peaky" so to speak...

I'd rather say "broad powerband". That is, close to peak hp output within a broad rpm range.

.hence the reason 4stroke yamis are so much better than their 2 stroke counterparts....just my opinion..but to say "torque doesn't matter" shows that you dont understand how engines work...torque definitely does matter....

And again, what matters is horsepower. I'll try this again. One engine has close to peak power from 8000 to 9000 rpm. The other has it from 11000 to 12500 rpm. Both have the same peak hp, and within a similary broad powerband. But the high-revving engine has lower maximum torque. The high-revving engine weighs 20 lbs less then the other engine.

Which engine would i prefer in a snowmobile ? The lighter one.

 

[morrisond]

A snowmobile is definitely not a Inifinite range CVT. That was just an example to show that torque is not what's matter the most since there's a gearbox, gearings between the engine and the driveshaft.

Your comparison of an 19,000 rpm 900 Hp F1 engine vs an 3,000 RPM 500 HP truck engine is not valid as they are not the same HP, the point many of us have been trying to make.

They're not the same hp in this example, but the F1 engine has much lower torque. Are you now saying that this isn't as important as hp ?

No but how can you compare two engines if you don't hold HP constant and vary torque? This is basically the choice Yammie engineers have. base the next Apex off an 1000 4 cyl and spin it at 12,000 RPM to get 170 hp or build an 3 cyl 1350cc at 8500 RPm to get the same 170 but an lot more torque.


The Audi Diesel can win Le-Mans because it's using much less gas (or diesel in this case). The Audi Diesel wouldn't stand a chance against a F1 car on a F1 track. Even if they put it in a F1 chassi.[/quote

There you are again making invalid comparisons. I was comparing an Gas F1 based engined Lemans racer with 650HP and say 300lbs of torque versus the Audi Diesel. Basically same type of cars, just different engines. Of course an F1 car would win on an F1 track, although it could be an lot more interesting at Lemans. The drag of an F1 car, due to it being optimized for downforce could severly limit it's top end on the Mulsanne straight, offsetting it's agility in the corners. This is besides the point though.

Would I like to see an 750CC gear reduced tripple? Sure I would like to try one, as it's big advantage is that with such small pistons and light valvetrain it might rev an lot faster. You would want to spin it at about 15-16,000 rpm to make enough power and then Gear reduce it by half to get sufficient Torque, but it would still only be in the 90lb ft range. I'm guessing at 15-16,000rpm an 750 would burn an lot more fuel than an 1050 at 8500 as welll.

 

[Laban]

This is basically the choice Yammie engineers have. base the next Apex off an 1000 4 cyl and spin it at 12,000 RPM to get 170 hp or build an 3 cyl 1350cc at 8500 RPm to get the same 170 but an lot more torque.

That's definitely a choice they have. And i'd take the 4 cyl without thinking about it, just for the much cooler sound. But you're missing the third option, the 750 cc high-revving 3 cyl solution that weighs much less..

Would I like to see an 750CC gear reduced tripple? Sure I would like to try one, as it's big advantage is that with such small pistons and light valvetrain it might rev an lot faster. You would want to spin it at about 15-16,000 rpm to make enough power and then Gear reduce it by half to get sufficient Torque, but it would still only be in the 90lb ft range. I'm guessing at 15-16,000rpm an 750 would burn an lot more fuel than an 1050 at 8500 as welll.

You wouldn't need anything close to 15-16000 rpm to make around 135 hp from a 750cc triple. I'm thinking that you could get that easily within the same rpm range as the Phazer. 120 hp is a given, then just do some tweaking , cam adjustments and so forth.

 

[morrisond]

Are we talking about an Nytro engine replacement or Apex? If we are talking about an 170 HP replacement for the Apex, you would need 15,000-16,000 rpm at least. the good thing is that you could possibly get about 110 lbs of torque at the clutch assuming an 2:1 reduction. It would sound very mean and remove anyones memories of 11,000 rpm 4 cylinders.

BTW go search the posts from last year before the Nytro was introduced I was an big advocate for the 750 tripple with Gear reduction.

I'm all for weight reduction in sleds. What intrigues me about the rumoured 3 cyl 1350 based on an YZ450 is that the YZ engine is very light. Assuming there are no differences in chasis there is only an 7lb weight dry weight weight difference between an YZ250 2 stroke and an YZ450 stroke.

I'm purely guessing but an 1350 tripple might even be lighter than 1000 4 which is where they may be getting an lot of there weight reduction.

 

[Laban]

Are we talking about an Nytro engine replacement or Apex?

What i was after was that horsepower is the only thing you need to worry about. Not only maximum hp of course but the whole power/rpm curve.
I was mainly thinking about a Nytro replacement though as an example.

BTW go search the posts from last year before the Nytro was introduced I was an big advocate for the 750 tripple with Gear reduction.

Good, we agree on something

I'm purely guessing but an 1350 tripple might even be lighter than 1000 4 which is where they may be getting an lot of there weight reduction.

The problem with this reasoning is that the 1350 triple is only a couple of lbs lighter then the Apex engine. Which makes me believe that a 1350cc <9500 rpm triple at 170 hp probably would be heavier then a 1000cc fourcylinder motor. And the sound of the fourbanger makes that an easy choice in my book.

And again, the higher torque of the 1350cc triple wouldn't necessarily be an advantage.

I'm all for weight reduction in sleds. What intrigues me about the rumoured 3 cyl 1350 based on an YZ450 is that the YZ engine is very light. Assuming there are no differences in chasis there is only an 7lb weight dry weight weight difference between an YZ250 2 stroke and an YZ450 stroke.

I don't think that a 3xYZ450 is the way to go myself. I'd much rather see a more modern Apex engine that's even more adapted for snowmobiling than it is now. I'm thinking that they could sacrifice some stability and loose another 5-10 lbs on the engine. Then do a 1050-1100 cc HO version with 170 hp.

 

[Yamaha205]

I would rather have the triple. I bet it gets better fuel mileage too.

Nothing beats the power of the 4cylinder. I dont care if its harder on gas as long as its faster than the others

 

[CROW]

Seems that this thread has gotten SLIGHTLY off track.

 

[SoCoRX1]

Ill take the 4cyl.

HP Sells sleds, not Torque.

 

[Mighty]

Have you ever raced a 120 hp Vector and a 145 hp RX-1? I have run 2 different RX-1s and two different Vectors several times with the same result. The Vector is surprisingly close to the RX-1 up to 90 mph. Beyond this the RX-1 S-L-O-W-L-Y walks away. This with a 25hp difference at basically the same weight.

1 big problem here; The RX-1 never made 145 HP. If I remember correctly they dynoed in the mid 130's...........

 

[QCRider]

Have you ever raced a 120 hp Vector and a 145 hp RX-1? I have run 2 different RX-1s and two different Vectors several times with the same result. The Vector is surprisingly close to the RX-1 up to 90 mph. Beyond this the RX-1 S-L-O-W-L-Y walks away. This with a 25hp difference at basically the same weight.

1 big problem here; The RX-1 never made 145 HP. If I remember correctly they dynoed in the mid 130's...........

As I recall, the '05 did.

 

[Mighty]

Have you ever raced a 120 hp Vector and a 145 hp RX-1? I have run 2 different RX-1s and two different Vectors several times with the same result. The Vector is surprisingly close to the RX-1 up to 90 mph. Beyond this the RX-1 S-L-O-W-L-Y walks away. This with a 25hp difference at basically the same weight.

1 big problem here; The RX-1 never made 145 HP. If I remember correctly they dynoed in the mid 130's...........

As I recall, the '05 did.

Nope.

 

[AndersY]

QCRider, morrisond and other torque fans:
Did you do the same in your physics classes as I did in my english classes - sleep?

Hp at the speeds that you're running is what matters. If you get it through high torque and low rpm, or low torque and high rpm doesn't matter at all.

Well, well, somewhat OT and I'm still hoping for a high-revving 750 cc triple, or maybe a 4 cyl 600 cc from R6. Both in the 120+ hp range.